Personal treatment devices are known that are equipped with a camera and that use captured camera images to control operation of the device. One example thereof is an interactive hair grooming apparatus as disclosed in US 20130021460. In operation, the known apparatus captures images of the targeted area, uses a translucent superimposed design overlay to determine whether the grooming style is correct, and, if this is not the case, automatically adjusts a grooming trimmer. This way of control is suitable for grooming, as it becomes visible whether or not an observed grooming style complies with a predetermined design style. In this way, it can easily be prevented that an area is treated multiple times, as the known control procedure would determine from the extent of compliance of the captured images with the design overlay whether or not an area had already been treated.
Contrary to this known treatment, many other skin treatments, such as photoepilation, do not result in a directly observable change in appearance of the skin of the body. A user of a device providing such a treatment may notice later that some areas were not treated. Users therefore may tend to overtreat the skin in order to avoid this. This is undesirable, as it implies that the user spends more time than usual to carry out the treatment. For battery-driven devices it implies that a smaller number of treatments can be performed until the battery needs to be recharged or replaced. In certain cases, an overtreatment may also result in skin irritation or even skin damage. A control procedure as used in the known apparatus would not be able to prevent this, as the camera images do not provide information indicating to what extent treatment was completed for the area in the field of view of the camera.